Mysql將查詢結果集轉換為JSON數據的實例代碼
Mysql將查詢結果集轉換為JSON數據 前言學生表學生成績表查詢單個學生各科成績(轉換為對象JSON串並用逗號拼接)將單個學生各科成績轉換為數組JSON串將數組串作為value並設置key兩張表聯合查詢(最終SQL,每個學生各科成績)最終結果
前言
我們經常會有這樣一種需求,一對關聯關系表,一對多的關系,使用一條sql語句查詢兩張表的所有記錄,例:一張學生表,一張學生各科成績表,我們想要用一條SQL查詢出每個學生各科成績;
學生表
CREATE TABLE IF NOT EXISTS `student`( `id` INT UNSIGNED AUTO_INCREMENT, `name` VARCHAR(100) NOT NULL PRIMARY KEY ( `id` ) )ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO student( id, name ) VALUES ( 1, '張三' ); INSERT INTO student( id, name ) VALUES ( 2, '李四' );
學生成績表
CREATE TABLE IF NOT EXISTS `score`( `id` INT UNSIGNED AUTO_INCREMENT, `name` VARCHAR(100) NOT NULL `student_id` INT(100) NOT NULL, `score` VARCHAR(100) NOT NULL PRIMARY KEY ( `id` ) )ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO score( id, name, student_id, score) VALUES ( 1, '數學', 1, '95.5' ); INSERT INTO score( id, name, student_id, score) VALUES ( 2, '語文', 1, '99.5' ); INSERT INTO score( id, name, student_id, score) VALUES ( 3, '數學', 2, '95.5' ); INSERT INTO score( id, name, student_id, score) VALUES ( 4, '語文', 2, '88' );
查詢單個學生各科成績(轉換為對象JSON串並用逗號拼接)
SELECT GROUP_CONCAT(JSON_OBJECT( 'id',id,'name',name,'student_id',student_id, 'score', score)) as scores FROM scroe where student_id = 1; ## 查詢結果 ## {"id": 1, "name": "數學", "student_id": 1, "score": "95.5"},{"id": 2, "name": "語文", "student_id": 1, "score": "99.5"}
將單個學生各科成績轉換為數組JSON串
SELECT CONCAT('[', GROUP_CONCAT(JSON_OBJECT( 'id',id,'name',name,'student_id',student_id, 'score', score)), ']') as scores FROM scroe where student_id = 1 ## 查詢結果 ## [{"id": 1, "name": "數學", "student_id": 1, "score": "95.5"},{"id": 2, "name": "語文", "student_id": 1, "score": "99.5"}]
將數組串作為value並設置key
SELECT CONCAT('{"scoreData":[', GROUP_CONCAT(JSON_OBJECT( 'id',id,'name',name,'student_id',student_id, 'score', score)), ']}') as scores FROM scroe where student_id = 1 ## 查詢結果 ## {"scoreData": [{"id": 1, "name": "數學", "student_id": 1, "score": "95.5"},{"id": 2, "name": "語文", "student_id": 1, "score": "99.5"}]}
兩張表聯合查詢(最終SQL,每個學生各科成績)
SELECT id, name, (SELECT CONCAT('[', GROUP_CONCAT(JSON_OBJECT( 'id',id,'name',name,'student_id',student_id, 'score', score)), ']') as scores FROM scroe WHERE student_id = stu.id) AS scores from student stu ## [{"id": 1, "name": "數學", "student_id": 1, "score": "95.5"},{"id": 2, "name": "語文", "student_id": 1, "score": "99.5"}]
最終結果
ID | NAME | SCORES |
---|---|---|
1 | 張三 | [{“id”: 1, “name”: “數學”, “student_id”: 1, “score”: “95.5”},{“id”: 2, “name”: “語文”, “student_id”: 1, “score”: “99.5”}] |
2 | 李四 | [{“id”: 3, “name”: “數學”, “student_id”: 1, “score”: “95.5”},{“id”:4, “name”: “語文”, “student_id”: 1, “score”: “88”}] |
到此這篇關於Mysql將查詢結果集轉換為JSON數據的文章就介紹到這瞭,更多相關mysql結果集轉換json數據內容請搜索WalkonNet以前的文章或繼續瀏覽下面的相關文章希望大傢以後多多支持WalkonNet!
推薦閱讀:
- None Found